Extend issue context popup beyond markdown content (#36908)

Extend the issue context popup beyond markdown. Any link rendered with
the `ref-issue` class now gets the popup, which covers commit titles and
issue titles everywhere they appear (repo home, commits list, blame,
branches, graph, PR commits, issue/PR pages, compare, …). For surfaces
that synthesize links without markdown autolinking (dashboard activity
feed, pulse page, commit merged-PR line), opt in by adding
`data-ref-issue-container` on a parent (or `ref-issue` on the link).

- Use `html_url` from the backend payload instead of synthesizing links
client-side
- Fetch outside the component, stateless, with a per-URL cache
- Small hover delay so passing over a link doesn't fire a request
- Drop the loading state (shifted layout)
- Make both links in the tooltip work; prevent nested tooltips
- Fix feed title `<a>` width so the tooltip only shows on link hover

Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>

templates/user/dashboard/feeds.tmpl

@@ -1,4 +1,4 @@
-<div id="activity-feed" class="flex-list">
+<div id="activity-feed" class="flex-list" data-ref-issue-container>
 	{{range .Feeds}}
 		<div class="flex-item">
 			<div class="flex-item-leading">
@@ -107,7 +107,7 @@
 				{{else if .GetOpType.InActions "create_pull_request"}}
 					<span class="tw-inline-block tw-truncate issue title">{{index .GetIssueInfos 1 | ctx.RenderUtils.RenderIssueSimpleTitle}}</span>
 				{{else if .GetOpType.InActions "comment_issue" "approve_pull_request" "reject_pull_request" "comment_pull"}}
-					<a href="{{.GetCommentLink ctx}}" class="tw-inline-block tw-truncate issue title">{{(.GetIssueTitle ctx) | ctx.RenderUtils.RenderIssueSimpleTitle}}</a>
+					<a href="{{.GetCommentLink ctx}}" class="tw-inline-block tw-truncate tw-self-start issue title">{{(.GetIssueTitle ctx) | ctx.RenderUtils.RenderIssueSimpleTitle}}</a>
 					{{$comment := index .GetIssueInfos 1}}
 					{{if $comment}}
 						<div class="render-content markup truncated-markup">{{ctx.RenderUtils.MarkdownToHtml $comment}}</div>